How to transfer Flower Garden to another device
By far the best way to transfer your garden to another device is to first do a backup through iTunes, and then do a “Restore from backup” from the new device. This is the only way to transfer your all you existing flowers, Fertilizer and Color Dust count.
The next best way is to use iCloud. If you have iCloud enabled on one device, you’ll have access to all the non-consumable purchases and unlocked seeds in all your other devices.
If those options aren’t possible, you can still get back all your garden and seed purchases that were not purchased with credit. In the new device, go to the Flower Shop, tap the top left button (Settings) and select “Restore Purchases”.
Log in to the same Game Center account you used before, and it will automatically restore all the achievements you had accomplished.